Advances in understanding biological systems have relied on applications of fluorescence microscopy, flow cytometry, versatile biological assays, and biosensors. These experimental approaches make extensive use of organic dye molecules as probes. But intrinsic limitations of these conventional dyes such as low absorptivity, and poor photostability have posed great difficulties in further developments of high-sensitivity imaging techniques and high-throughput assays. As a result, there has been considerable interest in developing brighter and more photostable fluorescent nanoparticles.
Traditional chromophoric polymer dots have been studied for imaging and detection techniques for researching chemical and biological analytes and systems. Functionalization of chromophoric polymer dots for use in bioconjugation has been attempted, but problems with polymer dot swelling, instability, and aggregation in biological buffer solutions, as well as nonspecific interactions in certain environments have been encountered.